This invention relates in general to power take-offs for selectively providing rotational energy from a source of rotational energy to a driven accessory. In particular, this invention relates to an improved structure for a combined power take-off and hydraulic pump assembly having a reduced overall length, weight, and number of parts.
A power take-off is a well known mechanical device that is often used in conjunction with a source of rotational energy, such as a vehicle engine or transmission, to provide rotational energy to a driven accessory. For example, power take-offs are commonly used in industrial and agricultural vehicles to provide rotational energy to hydraulic pumps that, in turn, are used to operate hydraulically driven accessories such as plows, trash compactors, lifting mechanisms, winches, and the like. The power take-off provides a simple, inexpensive, and convenient means for supplying energy from the source of rotational energy to the hydraulic pump that, in turn, provides relatively high pressure fluid to operate the driven accessory.
A typical power take-off includes an input mechanism and an output mechanism. The input mechanism of the power take-off is adapted to be connected to the source of rotational energy so as to be rotatably driven whenever the source of rotational energy is operated. The output mechanism of the power take-off is adapted to be connected to the hydraulic pump. In some instances, the input mechanism of the power take-off is directly connected to the output mechanism such that the hydraulic pump is rotatably driven whenever the source of rotational energy is operated. In other instances, a clutch assembly is provided between the input mechanism and the output mechanism such that the hydraulic pump is selectively driven only when the source of rotational energy is operated and the clutch assembly is engaged.
A typical hydraulic pump includes a fluid inlet port, a fluid outlet port, and a pumping mechanism. The fluid inlet port is adapted to communicate with a reservoir containing a quantity of relatively low pressure hydraulic fluid, while the fluid outlet port is adapted to communicate with the hydraulically driven device. The pumping mechanism of the hydraulic pump is adapted to be connected to the output mechanism of the power take-off so as to be rotatably driven whenever the power take-off is operated. Thus, when the power take-off is operated, the hydraulic pump draws relatively low pressure hydraulic fluid from the reservoir and supplies a flow of relatively high pressure hydraulic fluid to the hydraulically driven device.
The components of the power take-off are typically supported within a housing that is closed to retain lubricant and to prevent the entry of dirt, water, and other contaminants therein. In many instances, the power take-off housing is formed from first and second power take-off housing portions that are separate from one another, but are secured together to form a sealed enclosure for the components of the power take-off. For example, the first power take-off housing portion may be generally hollow in shape, having an opened end and a closed end, while the second power take-off housing portion may be generally flat and circular. The second power take-off housing portion can be secured to the first power take-off housing portion so as to close the opened end thereof and thereby form the power take-off housing. Such a two-piece structure facilitates the assembly and servicing of the components of the power take-off, and further allows either or both of the input and output mechanisms of the power take-off to be rotatably supported on the closed end of the first power take-off housing portion and the second power take-off housing portion.
The components of the hydraulic pump are typically supported within a housing that is closed to retain hydraulic fluid therein. In many instances, the hydraulic pump housing is formed from first and second hydraulic pump housing portions that are separate from one another, but are secured together to form a sealed enclosure for the components of the hydraulic pump. For example, the first hydraulic pump housing portion may be generally hollow and cylindrical in shape, having an opened end and a closed end, while the second hydraulic pump housing portion may be generally flat and circular. The second hydraulic pump housing portion can be secured to the first hydraulic pump housing portion so as to close the opened end thereof and thereby form the hydraulic pump housing. Such a two-piece structure facilitates the assembly and servicing of the components of the hydraulic pump, and further allows the components of the hydraulic pump to be rotatably supported on the first housing portion, while the input and output fluid ports are provided in the second hydraulic pump housing portion.
Typically, the power take-off and the hydraulic pump have been provided as separate, stand-alone devices, each having respective housings that support and protect the associated components therein. Thus, to create a combined power take-off and hydraulic pump assembly for selectively providing rotational energy from a source of rotational energy to a driven accessory, it is known to initially select both a stand-alone power take-off and a stand-alone hydraulic pump that are considered to be appropriate for the desired application. Then, the housing of the hydraulic pump is mounted on the housing of the power take-off to form the combined power take-off and hydraulic pump assembly.
Although the manufacture and assembly of a combined power take-off and hydraulic pump assembly in this manner has been satisfactory, the need has arisen to reduce the overall length, weight, and number of parts of the combined power take-off and hydraulic pump assembly. Thus, it would be desirable to provide an improved structure for a combined power take-off and hydraulic pump assembly having a reduced overall length, weight, and number of parts.